Add missing Welsh personalisations for confirmation email

[chao-xian]

What problem does this pull request solve?

A couple were missed from #2083

The Notify template will also need updating

Trello card: https://trello.com/c/NLqWmwvf/2894-update-confirmation-emails-to-cater-for-new-welsh-form-submissions

Things to consider when reviewing

• Ensure that you consider the wider context.
• Does it work when run on your machine?
• Is it clear what the code is doing?
• Do the commit messages explain why the changes were made?
• Are there all the unit tests needed?
• Do the end to end tests need updating before these changes will pass?
• Has all relevant documentation been updated?

[stephencdaly]

There's a failing test but otherwise looks good and still works locally. Will approve once the test is fixed.

[github-actions]

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